The nature of cytoplasmic vacuoles in chordoma cells. A correlative enzyme and electron microscopic histochemical study.
Enzyme histochemical study revealed that a sacrococcygeal chordoma not only was rich in oxidoreductive enzymes but also in the enzymes (phosphorylase, hexokinase, phosphoglucomutase, glucose phosphate isomerase and UDP-glucose dehydrogenase) leading to the synthesis of stromal glycosaminoglycans from glycogen. UDP-glucose dehydrogenase is particularly important in oxidizing UDP-glucose to UDP-glucuronic acid, the building block of hyaluronic acid and chondroitin sulfates. These enzymatic activities were consistent with the ultrastructural findings of abundant membrane-bound glycogen as well as large intracytoplasmic vacuoles with occasional residual glycogen particles. Furthermore, ultrastructural histochemical study using high iron diamine (HID) specifically localized the sulfated glycosaminoglycans (SG) extracellularly as well as intracellularly in distended Golgi saccules and 187-320 nm mature secretory vesicles. No HID staining was noted in the large intracytoplasmic vacuoles or rough endoplasmic reticulum. This study not only supports the hypothesis that the vacuoles of physaliphorous cells are the result of breakdown and utilization of membrane bound glycogen in the biosynthesis of SG, but also demonstrates that intracellular synthesis and storage of SG in chordoma are not in large vacuoles as previous investigators have believed.
Lam
R
R
Department of Pathology, Northwest Community Hospital, Arlington Heights, IL.
D000368:Aged; D001859:Bone Neoplasms / Q000201:enzymology / Q000648:ultrastructure*; D002817:Chordoma / Q000201:enzymology / Q000648:ultrastructure*; D003050:Coccyx; D003593:Cytoplasm / Q000648:ultrastructure*; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D012447:Sacrum; D014617:Vacuoles / Q000648:ultrastructure*